BUG: Placeholders not being filled on docstrings

doc/source/whatsnew/v1.2.1.rst

@@ -28,6 +28,7 @@ Fixed regressions
 - Fixed regression in :meth:`DataFrame.replace` raising ``ValueError`` when :class:`DataFrame` has dtype ``bytes`` (:issue:`38900`)
 - Fixed regression in :meth:`DataFrameGroupBy.diff` raising for ``int8`` and ``int16`` columns (:issue:`39050`)
 - Fixed regression that raised ``AttributeError`` with PyArrow versions [0.16.0, 1.0.0) (:issue:`38801`)
+- Fixed regression that caused templated docstrings to not get parsed (:issue:`39115`)
 -
 -
 

pandas/core/generic.py

@@ -9527,6 +9527,7 @@ def truncate(
         return result
 
     @final
+    @doc(klass=_shared_doc_kwargs["klass"])
     def tz_convert(
         self: FrameOrSeries, tz, axis=0, level=None, copy: bool_t = True
     ) -> FrameOrSeries:
@@ -10488,6 +10489,7 @@ def prod(
 
     product = prod
 
+    @doc()
     def mad(self, axis=None, skipna=None, level=None):
         """
         {desc}

pandas/util/_decorators.py

@@ -375,7 +375,7 @@ def decorator(decorated: F) -> F:
         decorated.__doc__ = "".join(
             [
                 component.format(**params)
-                if isinstance(component, str)
+                if isinstance(component, str) and params != {}
                 else dedent(component.__doc__ or "")
                 for component in docstring_components
             ]